UV‐laser‐based microscopic dissection of tree rings – a novel sampling tool for δ¹³C and δ¹⁸O studies

Abstract

SummaryUV-laser-based microscopic systems were utilized to dissect and sample organic tissue for stable isotope measurements from thin wood cross-sections.We tested UV-laser-based microscopic tissue dissection in practice for high-resolution isotopic analyses (d 13 C/d 18 O) on thin cross-sections from different tree species. The method allows serial isolation of tissue of any shape and from millimetre down to micrometre scales. Onscreen pre-defined areas of interest were automatically dissected and collected for mass spectrometric analysis. Three examples of high-resolution isotopic analyses revealed that: in comparison to d 13C of xylem cells, woody ray parenchyma of deciduous trees have the same year-to-year variability, but reveal offsets that are opposite in sign depending on whether wholewood or cellulose is considered; high-resolution tree-ring d 18O profiles of Indonesian teak reflect monsoonal rainfall patterns and are sensitive to rainfall extremes caused by ENSO; and seasonal moisture signals in intra-tree-ring d 18O of white pine are weighted by nonlinear intra-annual growth dynamics. The applications demonstrate that the use of UV-laser-based microscopic dissection allows for sampling plant tissue at ultrahigh resolution and unprecedented precision. This new technique facilitates sampling for stable isotope analysis of anatomical plant traits like combined tree eco-physiological, wood anatomical and dendroclimatological studies.

ENSO flavors in a tree-ring δ<sup>18</sup>O record of <i>Tectona grandis</i> from Indonesia

“…2b, c). Highresolution intra-annual δ 18 O TR analyses help to disentangle the contrasting isotope effects of dry and rainy season rainfall patterns, as demonstrated in Schollaen et al (2014). We conclude that the annually resolved tree-ring proxy is suitable for distinguishing between WP El Niño and La Niña, but not for CT El Niños.…”

“…The isotopic composition of precipitation (δ 18 O Pre ) over Java shows that distinct seasonal changes are linked to rainfall amount resulting in high δ 18 O Pre values during the dry season, and low δ 18 O Pre values during the rainy season ( Fig. 5b of Schollaen et al, 2014). Instrumental records (e.g., Aldrian and Susanto, 2003;Allan, 2000;Haylock and McBride, 2001) and reanalysis products (Aldrian et al, 2007;Jourdain et al, 2013) show rainfall anomalies in Indonesia are affected by ENSO: during a warm ENSO phase (El Niño events) the tropospheric air flow (Walker Circulation) weakens and the Indonesian low pressure system migrates eastward into the tropical Pacific, resulting in drought over much of the country.…”

“…In previous studies we investigated relationships between seasonal rainfall variability and tree-ring stable isotope records from Javanese teak trees on inter-to intra-annual timescales (Schollaen et al, 2013(Schollaen et al, , 2014. In this study we explore the signal strength of ENSO flavors in our annually resolved δ 18 O TR record from Java, the only well replicated, centennial δ 18 O record from Javanese teak in existence.…”

A remarkable relationship of the stable carbon isotopic compositions of wood and cellulose in tree-rings of the tropical species Cariniana micrantha (Ducke) from Brazil

“…The wood material of each tree-ring was dissected using a UV-laser dissection technique (Schollaen et al, 2014). Wood samples were homogenized with an ultra centrifugation mill (Retsch, ZM1, mesh size 0.05 mm), while the extracted α-cellulose was homogenized with an ultrasonic device (Laumer et al, 2009).…”

An optimized method for stable isotope analysis of tree rings by extracting cellulose directly from cross-sectional laths

“…They can be used to reconstruct paleoclimate (McCarroll and Loader, 2004;Grießinger et al, 2011;Xu et al, 2011;Sano et al, 2013) and study the expected responses of trees to climate change and elevated CO 2 (Kagawa et al, 2003;Saurer et al, 2004;Kirdyanov et al, 2008;Battipaglia et al, 2013), or used in place of tree-ring width measurements as alternative tools for cross-dating (Roden, 2008) or provenancing the geographical origins of timber (Kagawa and Leavitt, 2010). UV-laser micro dissection, a recent methodological breakthrough, enables analysis of tree rings at higher resolution (Schollaen et al, 2014). However, although stable isotope analysis has become cheaper and faster thanks to advances in mass spectrometry (Brenna et al, 1997;Farquhar et al, 1997;Saurer et al, 1998;Filot et al, 2006), the cellulose extraction process still remains the most laborious and time-consuming part of tree-ring isotope analysis.…”